This invention relates to a door lock, and more particularly to a door lock having a lever handle used in the case where a person having trouble in use of the hand can easily rotate the knob.
An example of conventional door locks of this kind is described in the U.S. Pat. No. 5,141,269 or the Japanese Published Patent Application No. 297681/1992 (Tokkaisho No. 4-297681).
The fundamental configuration of this example of prior art will now be described with reference to FIGS. 12 to 15.
Reference numeral 1 denotes a door pivotally supported by the door frame so that it can be opened. A door lock 2 having an inside lever handle 3 positioned on the indoor side and an outside lever handle 4 positioned on the outdoor side is attached on the door 1.
Moreover, reference numeral 5 denotes a lock body of door lock 2. An actual structure of the lock body 5 is described in the above-mentioned publication and the U.S. Pat. No. 4,604,879. Namely, the lock body 5 comprises a housing 7 opened at one side wall and having an annular wall 6 on the other side wall, a support frame (not shown) fixedly provided within the housing, a slide body 29 for a latch which is advanced or withdrawn within the support frame, an attachment block for a fixed plate having female screws, a bearing member, a rotary shaft, and the like.
Reference numeral 8 denotes a latch having a latch bolt 9 held by the latching slide body 29 of the lock body 5. This latch 8 is arranged along a latch axis 11 perpendicular to a handle axis 10 of lever handles 3, 4, as shown in FIG. 12. A front plate 12 opposite to a strike plate provided at the door frame (not shown) is provided at latch 8.
Reference numeral 13 denotes a cylindrical bearing member fixedly provided on housing 7 of lock body 5. This bearing member 13 has a male screw thread 14 at the outer circumferential surface, and is projected from annular wall 6 of the housing 7.
Reference numeral 15 denotes an outside fixed plate fixedly provided at the housing so that it is positioned at the opening side of the housing 7. This outside fixed plate 15 has a plurality-of projections 16 stuck into an outer wall 1a of door 1 at the internal surface thereof.
Reference numeral 17 denotes an inside fixed plate fixed through plural small screws 18 on the housing so that it is positioned on the annular wall 6 side of housing 7. This inside fixed plate 17-also has, at the inner surface thereof, a plurality of projections 19 stuck into inner wall 1b of door 1. The inside fixed plate 17 is securely fixed on the housing 7 by small screws 18 respectively penetrated through a pair of penetration holes 20 formed at the inside fixed plate and a plurality of penetration holes 21 formed at annular wall 6 of housing 7. The outside and inside fixed plates 15, 17 are caused to be opposite to each other when they are respectively thrust against wall surfaces 1a, 1b of door 1. It is to be noted that small screws 18 penetrate through apertures 21 of housing 7 and are screw-connected to female connections of the attachment block for the fixed plate (not shown) within housing 7.
Reference 22 denotes a hexagonally-shaped nut having a flange portion 23 in contact with the outer wall surface of inside fixed plate 17 and a tubular portion 25 penetrated through a center hole 24 of inside fixed plate 17.
This hexagonally shaped nut 22 has a female screw thread 26, which is screw-connected to the male screw thread 14 of the previously described bearing member 13. This hexagonally-shaped nut 22 serves to limit the inside fixed plate 17 so that it is located at a predetermined position, and to prevent small screws 18 from being loosened.
Reference numerals 27, 28 denote inside and outside tubular rotary shafts disposed on the handle shaft 10. The end portions of these rotary shafts 27, 28 are respectively combined into the lock body 5 to advance or withdraw the latching slide body 29 through engagement cam pieces 39 (best shown in FIGS. 14-15) formed at the inner end portions of the rotary shafts as projection therefrom. Further, inside and outside lever handles 3, 4 are respectively fitted over the outer end portions of said shafts having a plurality of cut portions (elongated openings) 27a, 27b, 27c, 28a, 28b, 28c. In addition, the retracting operation of the previously described latch bolt 9 is carried out by rotation of the inside or outside rotary shaft 27 or 28.
Reference numerals 30, 31 denote inside and outside return spring covers disposed on the handle shaft 10, respectively. These return spring covers 30, 31 are formed separately from fixed plates respectively disposed opposite thereto in this embodiment.
Moreover, these return spring covers 30, 31 have internally thereof spring members 32 for respectively returning lever handles 3, 4 to the initial positions. Further, these return spring covers 30, 31 have a pair of threaded nipples 33 projected from the inside walls, respectively. In addition, the inside return spring cover 30 and the outside return spring cover 31 are integrally connected through large screws 34 screw-connected to the female screw portions 33.
Reference numerals 35, 36 denote inside and outside decorative caps disposed on the handle shaft, respectively.
It is to be noted that reference numeral 38 denotes a turn button assembled into a penetration hole 37 of the inside lever handle 3. Further, reference numeral 40 denotes a cylinder lock fitted into the outside lever handle 4.
Meanwhile, cylinder lock 40 comprises an inner tube 41, an outer tube 42, an engagement piece 43 in a bar form, and one cover portion 44 in a projection form for accommodating a pin tumbler provided on the outer tube 42.
Moreover, an enlarged portion 48 having a slot 47 is formed on the handle 46 side of a tubular fitting portion 45 formed on outside lever handle 4.
Further, two engagement projections 49 are oppositely formed in a direction of handle axis 10 at the inner circumferential wall of the tubular fitting portion 45 as shown in FIG. 15.
In the above-mentioned configuration, two cut portions 28a, 28b oppositely disposed in the peripheral surface of outside rotary shaft 28 are respectively engaged with the two engagement projections 49, 49 of outside lever handle 4. Further, cover portion 44 of cylinder lock 40 is engaged with another cut portion 28c of outside rotary shaft 28.
Accordingly, when outside lever handle 4 is rotated, its rotational force is directly transmitted to the outside rotary shaft 28. As a result, outer tube 42 of cylinder lock 40 rotates along with outside rotary shaft 28 through a third cut portion of the outside rotary shaft in an unlatching (unlocking) state.
However, the door lock 2 thus constructed had the following drawbacks.
(1) Since cut portions 28a, for the drive are subject to a rotational force from the outside lever handle 4 and cut portion 28c with which cover portion 44 of cylinder lock 40 is engaged are respectively separately formed, there results an increased number of cut portions. Accordingly, the strength of the outer end portion of the outside rotary shaft 28 declines.
(2) When outside rotary shaft 28 rotates somewhat in the case where a burglar forcedly rotates outside lever handle 4 in one direction with cylinder lock 40 being in a latch (lock) state, the end surface of cut portion 28c directly comes into contact with the outer wall of cover portion 44 of cylinder lock 40. Accordingly, it is unable to sufficiently protect cover portion 44 of cylinder lock 40.
(3) In the case where outside lever handle 4 is rotated in an unlatching (unlocking) direction, outside rotary shaft 28 is rotated. As a result, latching slide body 29 is withdrawn into housing 7 of lock body 5 by the cam mechanism. Accordingly, when a burglar attempts to further forcedly rotate the outside lever handle 4 in excess of the limit (limiting point) of withdrawal movement of latching slide body 29, small screws 18 are deformed. For this reason, housing 7 of lock body 5 is separated from inside fixed plate 17 and is rotated by itself. Accordingly, latch bolt 9 of latch 8 disengaged from latching slide body 29 of lock body 5.
(4) Return spring covers 30, 31 and fixed plates 15, 17 are respectively formed as separate bodies. For that reason when it is necessary to fixedly attach fixed plates 15, 17 to housing 7, one is unable to attach door lock 2 to door 1 with ease.